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West Pacific/2015/11W/Archive/15
Public advisory TYPHOON NANGKA PUBLIC ADVISORY NUMBER 15 WIKI-HURRICANES FORECASTING CENTER 6:00 AM JST TUE JUL 07 2015 ...NANGKA JUST UNDER CATEGORY 3 INTENSITY... SUMMARY OF 12:00 AM JST...15:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...13.0N 155.8E CENTER POSITION CONFIDENCE: HIGH ABOUT 695 MI...1,120 KM ESE OF SAIPAN, MARIANA ISLANDS MAXIMUM SUSTAINED WINDS...95 KT...110 MPH...175 KM/H MINIMUM BAROMETRIC PRESSURE...948 MB...28.00 INCHES PRESENT MOVEMENT...W AT 11 KT...13 MPH...21 KM/H DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 6:00 am JST, the center of Typhoon Nangka was situated near 13.0N, 155.8E, or about 695 miles (1,120 km) east-southeast of Saipan, Mariana Islands. Maximum sustained winds were 95 knots (110 mph, 175 km/h), with higher gusts. The minimum barometric pressure was 948 millibars (hPa; 28.00 inHg), and the cyclone was tracking west-northwest at 11 knots (13 mph, 21 km/h). Additional intensification, perhaps rapid at times, is expected over the next 48 hours as Nangka remains steady in trajectory. NEXT ADVISORY ------------------- Next complete advisory at 12:00 pm JST. $$ Forecaster TAWX14 Discussion TYPHOON NANGKA DISCUSSION NUMBER 15 WIKI-HURRICANES FORECASTING CENTER 6:00 AM JST TUE JUL 07 2015 Typhoon Nangka is just under Category 3 intensity this morning. Satellite animations reveal that deep convection within the eyewall has become more prominent, especially within the southern quadrant. The eye, although still somewhat misshapen on conventional satellite, is well-defined on microwave imagery. Upper-level outflow has continued to expand in all quadrants except to the west. Recent satellite intensity estimates were T5.0/90kt from SAB and JTWC, and the most recent value from UW-CIMSS ADT at T6.1/117.4kt. Although a blend of these data would support 100kt, the initial intensity has instead been set at 95kt due to the fact that the ring of -70°C convection does not yet wrap fully around the eye. Maps from UW-CIMSS indicate that Nangka is undergoing a moderate 10 to 20 knots of wind shear via an upper-level trough to the cyclone's north-northwest. This shear may persist for another 36 to 48 hours as the upper-level trough drifts westward in tandem with the cyclone. Thereafter, the upper-level environment is forecast to become exceptionally conducive as the trough weakens. As such, the updated forecast follows the scheme of the previous one with steady intensification over the next 48 hours followed by a more rapid pace of strengthening thereafter. By the end of the forecast period, increasing wind shear courtesy of an upper-level trough diving east-southeastward across the northern West Pacific may cause Nangka to level off in intensity or even weaken slightly, although there are indications that the environment may once again become favorable in the longer term. Nangka is currently tracking swiftly west-northwest under the influence of a potent mid-level ridge across the northern West Pacific. This steering regime is expected to remain in place for the next 72 hours or so. Thereafter, the aforementioned upper-level trough is expected to erode the western periphery of the ridge and cause Nangka to turn more poleward at a slower rate. Both the GFS and ECMWF have shifted south since the previous advisory, and the updated track forecast is nudged in that direction. On its current path, Nangka is expected to pose a substantial threat to the northern and central Mariana Islands, and residents there should prepare for potentially life-threatening conditions. INIT 06/2100Z 13.0N 155.8E 95 KT 110 MPH 12H 07/0600Z 13.7N 154.4E 100 KT 115 MPH 24H 07/1800Z 14.4N 152.2E 105 KT 120 MPH 36H 08/0600Z 15.6N 150.1E 110 KT 125 MPH 48H 08/1800Z 17.0N 148.3E 115 KT 130 MPH 72H 09/1800Z 19.4N 144.4E 125 KT 145 MPH...NEAR NORTHERN MARIANA ISLANDS 96H 10/1800Z 20.8N 142.8E 135 KT 155 MPH 120H 11/1800Z 22.5N 141.9E 125 KT 145 MPH $$ Forecaster TAWX14